1. Field of the Invention
The invention relates to a method for operating a first or a second control device, which particularly serves to control a technical installation, where the operation of the first or second control device is undertaken with control data stored on a data medium in a predetermined format.
2. Description of the Related Art
The control devices, also comprising in some cases mobile devices, represent a human-machine interface (HMI) for controlling a technical installation. A control computer of the technical installation can be controlled via the control devices. To this end, the control devices have appropriate input and output means via which the technical installation can be observed, operated and controlled.
The functionalities of the control device are ensured with control data stored on a data medium. In the event of a technical defect of the control device, the data medium with the control data can then be removed from the defective control device and inserted into another control device. After the control data has been read out from the data medium, it is possible to control the technical installation with the new control device.
Although keeping the control data on the data medium allows rapid replacement of the control device, reading out and processing the control data stored on the data medium can be problematic with different versions of the control devices. Newer versions, especially of software, of the control devices frequently contain new features or changes to the existing features, which both frequently have an effect on the processing of the control data, such as through a changed data format.
Even if the control device can read out and process the control data stored on the data medium with a more up-to-date (software) version, a modification of the control data stored on the data medium can occur during the operation of the newer control device. After the data medium is replaced in a control device of the old version, under some circumstances it is no longer possible to read out the control data without problems.
In principle, it is known that control devices can be equipped with a newer version, i.e., newer software, such that this processes control data present in the “old format” on the data medium. The old format of the control data is preserved here both during reading and also during writing of data. This first-mentioned variant, in addition to a greater complexity of the software of the newer control device, leads to a deterioration of the qualitative properties during the operation of the new control device. For example, a longer start-up time, a longer time needed for the execution of operations and a higher use of resources occur. The more the new data format differs from the old data format, the greater are the negative effects.
As an alternative, the control data contained on the data medium can be adapted to the newer software version of the more up-to-date control device. To this end, the newer control device converts the control data into an optimal format for the software. At the same time, the control device with the older version, i.e., older software, must be expanded by the option for processing the control data present in the new data format on the data medium. This variant demands an expansion of the software of the old control device. If the control devices are used in safety-oriented installations, then any expansion of the functionality is to be verified by an assessor. This is complex and associated with high costs. In addition, the interaction of the first control device with such control devices as are compatible with the first control devices can no longer be guaranteed under some circumstances.